This invention relates to a drive for driving the injection pump for a fuel injected internal combustion engine and more particularly to an improved fuel injection pump arrangement for internal combustion engines.
Many forms of internal combustion engines now employ high pressure fuel injection pumps for spraying fuel into either the combustion chambers of the engine, as in the case of diesel or some gasoline engines, or for spraying fuel into the intake ports of the engine. Of course, the amount of fuel injected is extremely critical to engine operation and many times the engine is shut off and then restarted. If air is permitted to leak into the system and if the system is disposed in such a way that this air forms a trap between the fuel injection pump and the discharge nozzle, poor running or the impossibility of starting may result. These problems are particularly acute if the injection pump is oriented in such a way that its discharge nozzles are vertically positioned, i.e., at the highest vertical position of the fuel injection pump.
One type of engine in which fuel injection is utilized is an outboard motor. In an outboard motor, the engine normally operates in an orientation which is different from conventional engines. That is, in an outboard motor, the engine normally operates with its output shaft rotating about a vertically extending rather than a horizontally extending axis. This orientation of the engine gives rise to particular problems in connection with fuel injection systems.
In addition to the air lock problem described above, when a fuel injection pump is oriented vertically in an engine that has its output shaft also extending in a vertical direction, the piping from the fuel injection pump to the fuel injection nozzles become complicated. In addition, this type of orientation causes different lengths of distribution pipes running from the fuel injection pump to the fuel injection nozzles and this can result in unequal fuel distribution between the various cylinders of the engine.
In addition to the aforenoted problems, the provision of a vertically extending fuel injection pump coupled with an engine that has its output shaft rotating about a vertically extending axis gives rise to space problems, which are particularly acute in connection with outboard motors. That is, the driving arrangement for such a disposed fuel injection pump can either cause lengthening of the engine or at least lengthening of at least certain components of it such as the output shaft. In addition to requiring additional space, such vertical lengthening of the engine gives rise to an increased height which can undesirably offset the center of balance of the engine.
Furthermore, the vertical positioning of the fuel injection pump tends to cause the engine to become bulky even if it is not lengthened. That is, it is difficult to provide a compact internal combustion engine when the fuel injection pump extends along an axis that is parallel to the crankshaft axis and in which the engine is disposed vertically.
It is, therefore, a principal object of this invention to provide an improved fuel injection system for an internal combustion engine.
It is a further object of this invention to provide a fuel injection system for an internal combustion engine wherein the likelihood of air locks is minimized or substantially reduced.
It is a further object of this invention to provide an improved system for purging air from a fuel injection pump during its operation.
It is yet another object of this invention to provide a compact driving arrangement for the fuel injection pump of an internal combustion engine.
It is yet another object of this invention to provide an improved and compact arrangement for a fuel injection pump and its associated internal combustion engine.